Will Skylon Actually Fly?

[Der Anfang]

So, a spaceplane SSTO is in development by Reaction Engines Limited, and the project is none other than the Skylon. I'm sure a few of you have heard of it, no? The project looks very promising, and serious. If I am correct, they have demonstrated the cooling technology involved for the engines, which proved a success. I think the engines are theoretically possible, but actually building it and flying it is another story. Do you think this will fly successfully? I like how promising it looks, personally, but I am also a major skeptic. This is one of those things that you can only hope for to actually come true.

And ultimately, would this all be worth it?

[StrandedonEarth]

If it works, it would be worth it. And the fact that they are trying and have gotten one of the harder parts of the tech developed is encouraging. After all, anything that isn't tried will automatically fail.

Will it fly? They have some engineers that seem to think so, and have convinced some investors. One can only hope.

[Der Anfang]

If it works, it would be worth it. And the fact that they are trying and have gotten one of the harder parts of the tech developed is encouraging. After all, anything that isn't tried will automatically fail.

Will it fly? They have some engineers that seem to think so, and have convinced some investors. One can only hope.

If you ask me, a space elevator would be even more efficient, but an SSTO is a totally reasonable approach in this decade. We had our first successful powered flight in 1903, which before that, people thought it was impossible. 66 years later, we landed on the moon, and before we even touched the Karman line in the 40s, people thought it would be impossible to fire something in space. Nowadays, some people think SSTOs are impossible, but look at what history tells us now. If indeed REL builds this and successfully flies their first spaceplane (they hope to begin flying prototypes in '18 or '19), that will revolutionize everything, and we'd have an entirely new approach to getting into space. That would literally be the first step into getting an actual foothold toward mastering our own solar system.

Oh, also, according to an Article I read on their website, they got an £50 million grant to work more on developing their engine.

Edited October 12, 2015 by Der Anfang

[Rath]

I hope so. Skylon will make space cheaper. They want to sell single spaceplanes to some of the more stable african governments, which means that this will be infinity times cheaper that other launch vechiles.

[Nothalogh]

It's ambitious, but nothing about the proposal is glaringly lacking, thus the only obstacle I see is a failure of execution.

Which, of course is where nearly all projects fail.

So, roll the dice on that one.

I certainly hope it works, because if it does, the USAF will demand to have one of their own.

And so will begin the great SSTO race

[Der Anfang]

I hope so. Skylon will make space cheaper. They want to sell single spaceplanes to some of the more stable african governments, which means that this will be infinity times cheaper that other launch vechiles.

Flying a rocket to space and back is the equivalent of buying a new car to drive to work every day simply because it became expended during the trip. Rockets are cool, I'll admit. Rockets are awesome. But they are also dirty, inefficient, and money eaters.

It's ambitious, but nothing about the proposal is glaringly lacking, thus the only obstacle I see is a failure of execution.

Which, of course is where nearly all projects fail.

So, roll the dice on that one.

I certainly hope it works, because if it does, the USAF will demand to have one of their own.

And so will begin the great SSTO race

Oh, believe me. I'm skeptical. But they seem very serious about what they want to do, and the ambition is obvious. It also all boils down to money. They just got a huge grant, but even then, it's only enough to continue research on the SABRE, and to build the prototype components. And what is the USAF, exactly?

Edited October 12, 2015 by Der Anfang

[Nothalogh]

I hope so. Skylon will make space cheaper. They want to sell single spaceplanes to some of the more stable african governments, which means that this will be infinity times cheaper that other launch vechiles.

They want to sell single spaceplanes to some of the more stable african governments

some of the more stable african governments

stable african governments

I don't know whether to laugh or be worried

[Der Anfang]

I don't know whether to laugh or be worried

I am laughing. I can't take that seriously, lol.

[Nothalogh]

And what is the USAF, exactly?

The United States Airforce

[magnemoe]

I say they are too ambitious going directly for an SSTO.

I would rather made an reusable first stage first. Say you can not reach 9 km/s however say you can reach 4.5 km/s and 120 km attitude, here you release the second stage and the satellite who continues while the spaceplane continues on an ballistic trajectory and lands.

Much simpler and less demanding on payload fraction and much less reentry heat.

[Nothalogh]

I say they are too ambitious going directly for an SSTO.

I would rather made an reusable first stage first. Say you can not reach 9 km/s however say you can reach 4.5 km/s and 120 km attitude, here you release the second stage and the satellite who continues while the spaceplane continues on an ballistic trajectory and lands.

Much simpler and less demanding on payload fraction and much less reentry heat.

Reliable piggyback payload separation is suicidal at supersonic speeds, let alone hypersonic, read up on the M-21/D-21 project

[prophet_01]

You don't need piggyback for that kind of thing. A small scale version of scylon with a cargo bay (the real one is supposed to have one as well) should do the trick.

At this stage of the project reentry seems the biggest challenge. There aren't exactly a lot of practical and cheap examples of reusable reentry vehicles the size of a jumbo jet...

The space shuttles made very clear how difficult this is on regular flights. It's not just about safety, but about costs and maintenace requirements (personel, facilities, time for a complete check, etc). I have no idea how the Buran performed in this particular area, but I doubt that the revolutionized it.

So REL developed a new somewhat promising engine and the whole concept doesn't look too much like fantasy. That's great. But there is still a lot more to it.

And I'm still very sceptical about the idea of scylons being a part of every airport with a somewhat intact runway. Afterall it's not nearly as 'simple' as an airplane and it's certainly not a technology that has been optimised and fool proofed for more than a century. We don't even know the full scale of the infrastructure required for regular flights and maintenance.

[silent_prtoagonist]

One thing Skylon has going for it in terms of reentry is the fact that once it's massive hydrogen tanks are empty it'll have a very low overall density, which will do a lot to ease reentry heating compared to the denser space shuttle.

[magnemoe]

You don't need piggyback for that kind of thing. A small scale version of scylon with a cargo bay (the real one is supposed to have one as well) should do the trick.

At this stage of the project reentry seems the biggest challenge. There aren't exactly a lot of practical and cheap examples of reusable reentry vehicles the size of a jumbo jet...

The space shuttles made very clear how difficult this is on regular flights. It's not just about safety, but about costs and maintenace requirements (personel, facilities, time for a complete check, etc). I have no idea how the Buran performed in this particular area, but I doubt that the revolutionized it.

So REL developed a new somewhat promising engine and the whole concept doesn't look too much like fantasy. That's great. But there is still a lot more to it.

And I'm still very sceptical about the idea of scylons being a part of every airport with a somewhat intact runway. Afterall it's not nearly as 'simple' as an airplane and it's certainly not a technology that has been optimised and fool proofed for more than a century. We don't even know the full scale of the infrastructure required for regular flights and maintenance.

Yes, no piggyback but cargo bay and separation in space, no its not an orbital craft but it will still reach space, lower speed keeps the reentry problem down the lower requirements also let you get away with lower payload fraction.

For anything other than LEO you would need an second stage anyway.

Based on this early version you could learn more in how to make an real skylon.

[Nuke]

i like the engine but i really dont like the plane so much. i think they should focus on the engine itself and let someone else (like scaled composites) design a space craft around them. actual in flight testing might be carried out with a heavily modified sr71 testbed (cant think of another platform that could handle those flight regimes). im thinking keep the main engines and then put a scaled down sabre up on top of the fusalage. you dont have to put the thing in orbit, but it does let you test things like switching cycles on the fly, and test the engine throughout the various flight regimes.

[KSK]

You don't need piggyback for that kind of thing. A small scale version of scylon with a cargo bay (the real one is supposed to have one as well) should do the trick.

At this stage of the project reentry seems the biggest challenge. There aren't exactly a lot of practical and cheap examples of reusable reentry vehicles the size of a jumbo jet...

The space shuttles made very clear how difficult this is on regular flights. It's not just about safety, but about costs and maintenace requirements (personel, facilities, time for a complete check, etc). I have no idea how the Buran performed in this particular area, but I doubt that the revolutionized it.

So REL developed a new somewhat promising engine and the whole concept doesn't look too much like fantasy. That's great. But there is still a lot more to it.

And I'm still very sceptical about the idea of scylons being a part of every airport with a somewhat intact runway. Afterall it's not nearly as 'simple' as an airplane and it's certainly not a technology that has been optimised and fool proofed for more than a century. We don't even know the full scale of the infrastructure required for regular flights and maintenance.

Hmm, I don't think Reaction Engines ever mentioned anything about a 'somewhat intact runway'. Quite the opposite in fact, from their website:

"The vehicle takes off and lands using a relatively conventional retractable undercarriage. By special attention to the brake system it has proved possible to achieve an acceptably low undercarriage mass. A heavily reinforced runway will be needed to tolerate the high equivalent single wheel load."

I'm not sure where I read it but I seem to recall that Skylon will also need a longer than normal runway because it's take off speed is pretty high.

[prophet_01]

Yeah, I was exagerating with the runway thing. My point is that I doubt that the infrastructure required to launch a skylon involves a lot more than the regular airport can handle. Sure, you could ürobably add a specialised runway, maybe even the production facilities and storage tanks for the LF/O (cryogrnic), but there is still more stuff like specialised personel for the maintenace and checks, extra large hangars, etc.

I'm simply not buying the idea of selling skylons to nations that completely lack an aerospace industry (african countries or even half of the members of the EU seem to be out of the question). REL is overselling their product here imo.

I definitely agree that a suborbital skylon would be a reasonable first step in order to minimise the complexety of the design at this stage. It would be a good way to gather experience with the mostly untested technologies involved in order to ensure reliability and reasonable costs. It might even help to prevent critical design flaws with the final version which would be even more expensive at that stage of the project and it could help potential investors getting comfortable with the concept at an earlyer stage.

[Frozen_Heart]

I think the idea looks sounds, but it will never fly.

[Darnok]

I have seen video with different Skylon configuration, it had main Sabre engines, but in tail section was rocket engine to make final push to orbit.

Maybe hybrid with main jet engines and large tail section rocket engine would be better? Lynx can make suborbital flight just with rocket engine, Skylon would push it bit further? (I know Lynx is much much smaller)

[PB666]

dont know if it will fly or not, the link died, doesnt it need an http or something on the front?

http://www.reactionengines.co.uk/space_skylon.html

It can go up, doubtful that it can land.

Those engines are exposed during rentry, the would need to be a heat stable aperture on the to keep them from being trashed.

- - - Updated - - -

One thing Skylon has going for it in terms of reentry is the fact that once it's massive hydrogen tanks are empty it'll have a very low overall density, which will do a lot to ease reentry heating compared to the denser space shuttle.

Initial rentry doesn't care about density, is about velocity, and those engine nacells are going to take the brunt of erosion. They will simply degrade before hitting breathable atmosphere.

Edited October 12, 2015 by PB666

[KerikBalm]

Well, the payload fraction is pretty bad... what... 5%?

That could easily shrink down to 1% or 0% during the design phase... much like many VTOL fighter prototypes ended up heavier than anticipated and unable to lift any armament or reasonable amount of fuel.

So... how good is their estimate?

Then you think of the space shuttle... the only thing that wasn't reused was the ET... it seems like building a new ET shouldn't be so expensive relative to a full rocket... but the marginal.

Just look here:

https://en.wikipedia.org/wiki/Criticism_of_the_Space_Shuttle_program#Costs

" The final design differs from the original concept, causing, among other things, the shuttle orbiter to be almost 20% over its specified weight - resulting in it being unable to boost the US Air Force's payloads into polar orbits.[15]"

A 20% mass overrun would kill this design... a 5% mass overrun would kill the design

" Maintenance of the thermal protection tiles is a very labor-intensive and costly process, with some 35,000 tiles needing to be inspected individually and with each tile specifically manufactured for one specific slot on the shuttle.[16]"

I don't know what sort of heat protection system they will have, but it could end up being very expensive for the small payload delivered.

" The Space Shuttle Main Engines (SSMEs) were highly complex and maintenance-intensive, necessitating removal and extensive inspection after each flight. Before the "Block II" engines, the turbopumps (a primary engine component) had to be removed, disassembled, and totally overhauled after each flight.[citation needed]"

The SABRE engines will likely be even more complex and expensive to maintain.

" The toxic propellants used for the OMS/RCS thrusters required special handling, during which time no other activities could be performed in areas sharing the same ventilation system. This increased turn-around time.[citation needed]"

What will its OMS/RCS be? the same I guess

" The launch rate was significantly lower than initially expected. While not reducing absolute operating costs, more launches per year gives a lower cost per launch. Some early hypothetical studies examined 55 launches per year (see above), but the maximum possible launch rate was limited to 24 per year based on manufacturing capacity of the Michoud facility that constructs the external tank. Early in shuttle development, the expected launch rate was about 12 per year.[17] Launch rates reached a peak of 9 per year in 1985 but averaged fewer thereafter."

This shouldn't be a problem

" When the decision was made on the main shuttle contractors in 1972, work was spread among companies to make the program more attractive to Congress, such as the contract for the Solid Rocket Boosters to Morton Thiokol in Utah. Over the course of the program, this raised operational costs,[citation needed] though the consolidation of the US aerospace industry in the 1990s means the majority of the Shuttle was now with one company: the United Space Alliance, a joint venture of Boeing and Lockheed Martin.""

This shouldn't be a problem for Skylon

Still lots of potential problems for Skylon.

To top it off, it will now be competing with reusable boosters from Space X, and other companies are developing tech to reuse their boosters too.

[Rune]

So, a spaceplane SSTO is in development by Reaction Engines Limited, and the project is none other than the Skylon. I'm sure a few of you have heard of it, no? The project looks very promising, and serious. If I am correct, they have demonstrated the cooling technology involved for the engines, which proved a success. I think the engines are theoretically possible, but actually building it and flying it is another story. Do you think this will fly successfully? I like how promising it looks, personally, but I am also a major skeptic. This is one of those things that you can only hope for to actually come true.

And ultimately, would this all be worth it?

The biggest hurdle is actually forming an aerospace conglomerate that can fund this monster of a program (unlikely), or get one of the big boys involved (even less likely, Not Invented Here syndrome). Technically? The engineering is easy by comparison. As the saying goes, we can lick gravity, but sometimes the paperwork is overwhelming.

In any case, a reusable launch system only makes sense if you plan to do this "space thing" a lot. then again, once you make it barely economical, it can only get better from then on, so assuming a non-stagnant aerospace industry, yeah, eventually it will make a lot of sense. When? That one is a bit more dubious.

i like the engine but i really dont like the plane so much. i think they should focus on the engine itself and let someone else (like scaled composites) design a space craft around them. actual in flight testing might be carried out with a heavily modified sr71 testbed (cant think of another platform that could handle those flight regimes). im thinking keep the main engines and then put a scaled down sabre up on top of the fusalage. you dont have to put the thing in orbit, but it does let you test things like switching cycles on the fly, and test the engine throughout the various flight regimes.

That is exactly what Reaction Engines is doing. Mind you, they played with numbers and developed a very nice notional design (the one we are talking about), but that is, I suspect, what they do in their free time. Their resources so far have gone into the engine development effort, most notably the precooler. Alan Bond and other have often said that Reaction Engines would not develop the Skylon, not even the whole engine, but rather be part of a consotrium to build the thing, with someone like Rolls Royce finishing the engine including integration and someone else doing the airframe. It is a BIG development program.

I have seen video with different Skylon configuration, it had main Sabre engines, but in tail section was rocket engine to make final push to orbit.

Maybe hybrid with main jet engines and large tail section rocket engine would be better? Lynx can make suborbital flight just with rocket engine, Skylon would push it bit further? (I know Lynx is much much smaller)

The difference between Lynx and Skylon is, literally, orders of magnitude. It takes a boopload more energy to go up to 7.2km/s (orbital speed on LKO) than to pop out of the atmosphere at less than a km/s. And yeah, Skylon has a small LH2/LOX engine for orbital maneuvers, the SABREs are hugely oversized for that and I don't know about their restarting capabilities.

You don't need piggyback for that kind of thing. A small scale version of scylon with a cargo bay (the real one is supposed to have one as well) should do the trick.

At this stage of the project reentry seems the biggest challenge. There aren't exactly a lot of practical and cheap examples of reusable reentry vehicles the size of a jumbo jet...

The space shuttles made very clear how difficult this is on regular flights. It's not just about safety, but about costs and maintenace requirements (personel, facilities, time for a complete check, etc). I have no idea how the Buran performed in this particular area, but I doubt that the revolutionized it.

So REL developed a new somewhat promising engine and the whole concept doesn't look too much like fantasy. That's great. But there is still a lot more to it.

And I'm still very sceptical about the idea of scylons being a part of every airport with a somewhat intact runway. Afterall it's not nearly as 'simple' as an airplane and it's certainly not a technology that has been optimised and fool proofed for more than a century. We don't even know the full scale of the infrastructure required for regular flights and maintenance.

Compared to Skylon, Shuttle and Buran had an awful ballistic coefficient (as in, several times higher). And it still shed most of its speed way higher than any capsule, experiencing peak temperatures commensurately lower, for a longer period of time. Thus, it could use non-ablating C-C composites as leading edges, and it had an internal cooling system to handle the extended heat load on the inner aluminum structure. I encourage you to google all the terms I just cited and go for the wiki links, especially "ballistic coefficient".

Snip

You totally asked for a point-by-point answer...

" The final design differs from the original concept, causing, among other things, the shuttle orbiter to be almost 20% over its specified weight - resulting in it being unable to boost the US Air Force's payloads into polar orbits.[15]"

A 20% mass overrun would kill this design... a 5% mass overrun would kill the design

Yup, that is one of the main problems. Then again, all rockets have payload fractions on the order of 5% of launch mass, so they all have the same risk on their development stage. Granted, with a "slightly" relaxed requirement . What can I say, It'll be a hell of a development program, and it might not work. But if you throw enough money at the problem, you'd be surprised the kind of stuff people can come up with.

" Maintenance of the thermal protection tiles is a very labor-intensive and costly process, with some 35,000 tiles needing to be inspected individually and with each tile specifically manufactured for one specific slot on the shuttle.[16]"

I don't know what sort of heat protection system they will have, but it could end up being very expensive for the small payload delivered.

Which is often mentioned by Bond, and is something they took care to design out of their thing.The structure and the thermal protection systems are isolated from each other, and the skin is made up of metallic panels and C-C composites. Bond himself, though, has said that this is a place where someone could step in and try to improve, because they only looked at commercially available materials. I think those were his words, but I'm going form memory, so feel free to look it up on his interviews on youtube and such.

" The Space Shuttle Main Engines (SSMEs) were highly complex and maintenance-intensive, necessitating removal and extensive inspection after each flight. Before the "Block II" engines, the turbopumps (a primary engine component) had to be removed, disassembled, and totally overhauled after each flight.[citation needed]"

The SABRE engines will likely be even more complex and expensive to maintain.

Yup, they will be burdensome beasts. Their target design life is on the same order of magnitude as commercial jet engines! Still , this is what these guys do, propulsion engineering, and they already delivered the impossible with their precoolers. If Alan Bond says that is achievable, I'm inclined to say he won't be far off.

" The toxic propellants used for the OMS/RCS thrusters required special handling, during which time no other activities could be performed in areas sharing the same ventilation system. This increased turn-around time.[citation needed]"

What will its OMS/RCS be? the same I guess

It uses gaseous hydrogen/LOX attitude thrusters, as well as fuel cells for power generation. I guess the integrated fluids concepts of Boeing for ACES caught their eye at some point. It is an elegant system, using tank residuals for everything.

" The launch rate was significantly lower than initially expected. While not reducing absolute operating costs, more launches per year gives a lower cost per launch. Some early hypothetical studies examined 55 launches per year (see above), but the maximum possible launch rate was limited to 24 per year based on manufacturing capacity of the Michoud facility that constructs the external tank. Early in shuttle development, the expected launch rate was about 12 per year.[17] Launch rates reached a peak of 9 per year in 1985 but averaged fewer thereafter."

This shouldn't be a problem

Yeah, this actually should be a problem. Skylon needs a huge market to work economically, and it won't be built until that is proven. And since it may well take something like Skylon to create such a huge market, this could be a chicken and egg problem. One hopes the plethora of reusable first stages in the works right now can succeed and let the concept get more traction, and the market grows accordingly...

" When the decision was made on the main shuttle contractors in 1972, work was spread among companies to make the program more attractive to Congress, such as the contract for the Solid Rocket Boosters to Morton Thiokol in Utah. Over the course of the program, this raised operational costs,[citation needed] though the consolidation of the US aerospace industry in the 1990s means the majority of the Shuttle was now with one company: the United Space Alliance, a joint venture of Boeing and Lockheed Martin.""

This shouldn't be a problem for Skylon

This should be a big problem for Skylon. Such a big program is inherently political, and the UK hasn't got the bucks to go at this alone. And elsewhere, they are gong to run into the Not-Invented-Here syndrome, fast. And we all know how well European consortia work...

Rune. Still, it is a smexy concept. A geek can hope!

Edited October 12, 2015 by Rune
Really, I dont' get why that word is censored

[_Augustus_]

I think that if it flies, it will be really good for NASA because they will be able to afford a new LEO space station along with the EML-2 outpost.

[Der Anfang]

Well, the payload fraction is pretty bad... what... 5%?

That could easily shrink down to 1% or 0% during the design phase... much like many VTOL fighter prototypes ended up heavier than anticipated and unable to lift any armament or reasonable amount of fuel.

So... how good is their estimate?

Then you think of the space shuttle... the only thing that wasn't reused was the ET... it seems like building a new ET shouldn't be so expensive relative to a full rocket... but the marginal.

Just look here:

https://en.wikipedia.org/wiki/Criticism_of_the_Space_Shuttle_program#Costs

" The final design differs from the original concept, causing, among other things, the shuttle orbiter to be almost 20% over its specified weight - resulting in it being unable to boost the US Air Force's payloads into polar orbits.[15]"

A 20% mass overrun would kill this design... a 5% mass overrun would kill the design

" Maintenance of the thermal protection tiles is a very labor-intensive and costly process, with some 35,000 tiles needing to be inspected individually and with each tile specifically manufactured for one specific slot on the shuttle.[16]"

I don't know what sort of heat protection system they will have, but it could end up being very expensive for the small payload delivered.

" The Space Shuttle Main Engines (SSMEs) were highly complex and maintenance-intensive, necessitating removal and extensive inspection after each flight. Before the "Block II" engines, the turbopumps (a primary engine component) had to be removed, disassembled, and totally overhauled after each flight.[citation needed]"

The SABRE engines will likely be even more complex and expensive to maintain.

" The toxic propellants used for the OMS/RCS thrusters required special handling, during which time no other activities could be performed in areas sharing the same ventilation system. This increased turn-around time.[citation needed]"

What will its OMS/RCS be? the same I guess

" The launch rate was significantly lower than initially expected. While not reducing absolute operating costs, more launches per year gives a lower cost per launch. Some early hypothetical studies examined 55 launches per year (see above), but the maximum possible launch rate was limited to 24 per year based on manufacturing capacity of the Michoud facility that constructs the external tank. Early in shuttle development, the expected launch rate was about 12 per year.[17] Launch rates reached a peak of 9 per year in 1985 but averaged fewer thereafter."

This shouldn't be a problem

" When the decision was made on the main shuttle contractors in 1972, work was spread among companies to make the program more attractive to Congress, such as the contract for the Solid Rocket Boosters to Morton Thiokol in Utah. Over the course of the program, this raised operational costs,[citation needed] though the consolidation of the US aerospace industry in the 1990s means the majority of the Shuttle was now with one company: the United Space Alliance, a joint venture of Boeing and Lockheed Martin.""

This shouldn't be a problem for Skylon

Still lots of potential problems for Skylon.

To top it off, it will now be competing with reusable boosters from Space X, and other companies are developing tech to reuse their boosters too.

They're using a porcelain composite material for reentry heating. I don't think they are using tiles like the space shuttle.

[cantab]

I think the British government -

Oh noes! Politics!

We continue to be gagged from meaningful discussion of space exploration on a forum about a space game.